Known in the art is a method for producing reactive peroxidized copolymers by means of mass copolymerization or suspension copolymerization of vinyl monomers with perester acrylates (cf. USSR Inventor's Certificate No. 170,675 published in Bulletin "Otkrytia, izobretenia, promyshlennye obraztsy i tovarnye znaki", No 9, 1965, p. 69). According to this method, 1-10% of monomeric peroxide is added to vinyl monomer and the reaction mixture is heated in autoclaves at a temperature ranging from 40.degree. to 100.degree. C. The copolymer formed comprises 0.1-3% of the peroxidic groups. The copolymers obtained according to this method have low reactivity due to a small content of the peroxidic groups therein because of their decomposition during synthesis of the copolymers. In further use of said copolymers to obtain graft copolymers, their low reactivity fails to provide the grafting extent required.
Also known in the art is a method for producing reactive latices by means of copolymerization of vinyl monomers with butyl-2-acrylate-ethyl peroxide (cf. a paper by Puchin V. A. et al. Syntaz perekisnosoderzhashikh divinylstyrolnikh sopolymerof v emulsiyakh. Visokomoleculijrnie soedineniij. AII, 1969, No. 4, pp. 789-793). By this method, the copolymerization of vinyl monomers with peroxidic monomer (in amount of 1-5 mole, %) is carried out in an emulsion stabilized with ammonium cetyl trimethyl bromide at temperatures of from 10.degree. to 50.degree. C. The copolymer formed comprises 0.1-2% of the peroxidic units.
The copolymers obtained according to this method have low reactivity due to a small content of the peroxidic groups in the copolymers.
Known in the art is a method for producing latices of reactive alkyl acrylate rubbers by means of emulsion copolymerization of alkyl acrylate with a bifunctional acrylic monomer, such as .beta.-chloroethyl methacrylate or glycidyl methacrylate (cf. USSR Inventor's Certificate No. 254,770 published in Bulletin "Otkrytia, izobretenia, promyshlennye obraztsy i tovarnye znaki", No. 32, 1969, p. 81). Copolymerization of styrene, butyl acrylate and .beta.-chloroethyl methacrylate is carried out in emulsion at a ratio of the water phase to the hydrocarbon phase of 2:1 or 4:1, in the presence of an emulsifier, such as sodium alkyl sulfonate, and a redox system at a reaction temperature of from 30.degree. to 70.degree. C. In 2-2.5 hours, conversion of the monomers amounts to 95-98%.
Introduction of .beta.-chloroethyl methacrylate units into macrochains of the butyl acrylate rubber causes rapid aging of these rubbers. According to this method, grafting to the butyl acrylate rubber containing chlorine atoms occurs due to the chain transfer reaction as a result of the separation of the chlorine atom. However, low efficiency of this reaction results in inadequate grafting of vinyl monomers to the butyl acrylate rubber.
There is known a method for producing latices of alkyl acrylate rubbers used primarily in synthesizing shock-proof copolymers based on vinyl monomers (cf. USSR Inventor's Certificate No. 447,050 published in Bulletin "Otkrytia, izobretenia, promyshlennye obraztsy i tovarnye znaki", No. 31, 1976, p. 177). By this method, rubber latices are prepared by emulsion copolymerization of acrylic monomers with 1-(.alpha.-alkyl acrylate)-1-tertbutyl peroxy ethanes in the presence of water soluble emulsifiers and a reversible initiating redox system consisting of isopropyl benzene hydroperoxide, Rongalite.RTM., and Trilon B.RTM., the components all being simultaneously introduced into the reactor.
As a result of the copolymerization, there are formed alkyl acrylate rubber latices having peroxidic side groups capable of grafting vinyl monomers.
The exothermal nature of the copolymerization of the above method (which increases the temperature up to 50.degree.-60.degree. C.) results in decomposition of the peroxidic groups during the latex synthesis up to 25%, which requires additional heat-removal.
The rubber latex, produced in accordance with the above method, exhibits low stability stored, manifesting itself in decomposition of the peroxidic groups entering into the structure of the rubber, and decreases the further ability of the rubber to graft vinyl monomers. Due to such a feature, the latex cannot be used but immediately after its synthesis.
A high rate of copolymerization in accordance with the above-mentioned method, namely the copolymer yield in 15 minutes amounts to 70-80%, makes it difficult to control dispersity of the latex being formed.
These disadvantages manifest themselves particularly in the cases, when the most available peroxidic monomer, i.e. 1-methacrylate-1-tert-butyl peroxy ethane is used as 1-(.alpha.-alkyl acrylate)-1-tert-butyl peroxy ethane.